Fire Barrier Layer And Fire Barrier Film Laminate

ABSTRACT

A fire barrier laminate including: at least one non-fibrous fire barrier layer directly or indirectly coated onto at least one first polymeric flame propagation resistant film layer; at least one second film layer proximate to the non-fibrous fire barrier layer opposite the first polymeric flame propagation resistant film layer; at least one scrim layer disposed: (i) between the non-fibrous fire barrier layer and the first polymeric flame propagation resistant film layer; and/or (ii) between the non-fibrous fire barrier layer and the second film layer; and/or (iii) proximate to the first polymeric flame propagation resistant film layer opposite the non-fibrous fire barrier layer; and/or (iv) proximate to the second film layer opposite the non-fibrous fire barrier layer. Also, a method of making the fire barrier laminate.

This application is a divisional application of U.S. Ser. No. 13/299,399, filed on Nov. 18, 2011, which claims the benefit of the filing date under 35 U.S.C. §119(e) from U.S. Provisional Application For Patent Ser. No. 61/415,552 filed on Nov. 19, 2010.

A fire barrier laminate is provided for use in thermal and acoustical insulation systems, such as, but not limited to, those used in commercial aircraft.

The Federal Aviation Administration (FAA) has promulgated regulations, contained in 14 C.F.R. §25.856(a) and (b), requiring thermal and acoustical insulation blanket systems in commercial aircraft to provide improved burn through protection and flame propagation resistance. These conventional thermal and acoustical insulation systems typically include thermal and acoustical insulation blankets encapsulated within a film covering or bag. As the thermal and acoustical insulation systems are conventionally constructed, the burn through regulations primarily affect the contents of the insulation systems' bags and the flame propagation resistance regulations primarily affect the film coverings used to fabricate the bags. Conventional film coverings typically are used as a layer or covering, for example, laid over or laid behind layers of thermal and acoustical insulation material, or as a covering or bag for partially or totally encapsulating one or more layers of thermal and acoustical insulation material.

FIG. 1A is a schematic cross-sectional view of a thermal and acoustical aircraft insulation blanket protected by an embodiment of the subject fire barrier laminate.

FIG. 1B is an exploded cross-sectional view of an illustrative embodiment of the subject fire barrier laminate circled portion B′ of the embodiment of FIG. 1A.

FIG. 1C is an exploded cross-sectional view of another illustrative embodiment of the subject fire barrier laminate circled portion B′ of the embodiment of FIG. 1A.

FIG. 1D is an exploded cross-sectional view of a further illustrative embodiment of the subject fire barrier laminate circled portion B′ of the embodiment of FIG. 1A.

FIG. 1E is an exploded cross-sectional view of a further illustrative embodiment of the subject fire barrier laminate circled portion B′ of the embodiment of FIG. 1A.

A fire barrier layer is provided which is incorporated into a fire barrier laminate for use in thermal and acoustical insulation systems, such as, but not limited to, those used in commercial aircraft. By way of example, but not limitation, the fire barrier laminate may be used as a covering that is located between insulation material in fuselage wall cavities and the outer skin of an aircraft fuselage (as an outboard cover of an insulation system) and/or between insulation material in fuselage wall cavities and the interior aircraft trim panels (as an inboard cover of an insulation system).

The incorporation of the subject fire barrier layer in a fire barrier laminate, used for protecting thermal and acoustical insulation structures, solves problems previously associated with the use of lightweight ceramic or inorganic papers, which tend to be fragile to handling or in use where harsh mechanical environments are encountered.

In certain embodiments, the subject fire barrier film laminate comprises at least one non-fibrous fire barrier layer coated onto at least one film layer, optionally a water-repellant material incorporated into and/or applied to the fire barrier layer, at least one scrim layer, at least one second film layer, and optionally at least one adhesive layer, the non-fibrous fire barrier layer comprising at least one inorganic platelet material, optionally at least one organic binder and/or inorganic binder, and optionally at least one functional filler.

In certain embodiments, the fire barrier laminate comprises: at least one non-fibrous fire barrier layer directly or indirectly coated onto at least one first polymeric flame propagation resistant film layer; at least one second film layer proximate to the non-fibrous fire barrier layer opposite the first polymeric flame propagation resistant film layer; at least one scrim layer disposed: (i) between the non-fibrous fire barrier layer and the first polymeric flame propagation resistant film layer; and/or (ii) between the non-fibrous fire barrier layer and the second film layer; and/or (iii) proximate to the first polymeric flame propagation resistant film layer opposite the non-fibrous fire barrier layer; and/or (iv) proximate to the second film layer opposite the non-fibrous fire barrier layer; optionally, a water-repellant material incorporated into and/or applied to the non-fibrous fire barrier layer; optionally at least one adhesive layer adhering the non-fibrous fire barrier layer to the first polymeric flame propagation resistant film layer; and optionally at least one adhesive layer adhering the scrim layer to at least one of the non-fibrous fire barrier layer, the first polymeric flame propagation resistant film layer, or the second film layer; wherein the non-fibrous fire barrier layer comprises at least one inorganic platelet material, optionally at least one organic binder and/or inorganic binder, and optionally at least one functional filler. Optionally, the second film layer may also be flame propagation resistant.

By indirectly coating, it is meant that the non-fibrous fire barrier layer may be coated onto an intermediate layer, such as a scrim, wherein the intermediate layer is engaged with the first polymeric flame propagation resistant film layer. The intermediate layer may be engaged with the first polymeric flame propagation resistant film layer before or after being coated with the non-fibrous fire barrier layer.

This composition provides a light basis weight article with surprising resistance to damage associated with handling and use along with the ability to resist flame propagation and flame penetration as defined in 14 C.F.R. §25.856(a) and (b). The term “basis weight” is defined as the weight per unit area, typically defined in grams per square meter (gsm). The subject fire barrier layer, and the laminate incorporating it, are therefore useful in providing fire burn-through protection for thermal and acoustical insulation structures, referred to in the industry as “blankets”, for commercial aircraft fuselages, as the subject fire barrier laminate may have a basis weight of between about 80 gsm to about 120 gsm, and in certain embodiments between about 90 gsm to about 110 gsm.

The inorganic platelet material of the fire barrier layer may comprise at least one of vermiculite, mica, clay or talc. While any size inorganic platelet material may be used, inorganic platelet materials with larger relative diameters and high diameter to thickness aspect ratios may be desirable due to their increased flame propagation and/or burnthrough resistance performance, as well as other properties such as flexibility and processibility. In certain embodiments, the inorganic platelet material may have a diameter of from about 20 μm to about 300 μm. In further embodiments, the inorganic platelet material may have a diameter of from about 40 μm to about 200 μm. In certain embodiments, the inorganic platelet material may have an aspect ratio of from about 50:1 to about 2000:1. In certain embodiments, the inorganic platelet material may have an aspect ratio of from about 50:1 to about 1000:1. In further embodiments, the inorganic platelet material may have an aspect ratio of from about 200:1 to about 800:1.

The vermiculite or mica may be exfoliated, and may further be defoliated. By exfoliation, it is meant that the vermiculite or mica is chemically or thermally expanded. By defoliation, it is meant that the exfoliated vermiculite or mica is processed in order to reduce the vermiculite or mica to substantially a platelet form. Vermiculite may be included in the fire barrier layer in an amount from about 20 to about 100 weight percent, based on the total weight of the fire barrier layer.

Suitable micas may include, without limitation, muscovite, phlogopite, biotite, lepidolite, glauconite, paragonite and zinnwaldite, and may include synthetic micas such as fluorophlogopite. Mica may be included in the fire barrier layer in an amount from about 20 to about 100 weight percent, based on the total weight of the fire barrier layer.

Suitable platelet clay materials that may be included in the fire barrier layer include, without limitation, ball clay, bentonite, smectite, hectorite, kaolinite, montmorillonite, saponite, sepiolite, sauconite, or combinations thereof. Platelet clay materials may be included in the fire barrier layer in an amount from about 5 to about 60 weight percent, in certain embodiments from about 5 to about 50 weight percent, based on the total weight of the fire barrier layer.

The mica, vermiculite and/or clay platelet materials may also be combined with further platelet materials, such as talc. If present, talc may be included in the fire barrier layer in an amount from about 1 to about 50 weight percent, in certain embodiments, from about 10 to about 30 weight percent, based on the total weight of the fire barrier layer.

The fire barrier layer may include inorganic binders. Without limitation, suitable inorganic binders include colloidal dispersions of alumina, silica, zirconia, and mixtures thereof The inorganic binders, if present, may be used in amounts ranging from 0 to about 40 percent by weight, in some embodiments from 0 to about 20 weight percent, based upon the total weight of the fire barrier layer.

The fire barrier layer may further include one or more organic binders. The organic binder(s) may be provided as a solid, a liquid, a solution, a dispersion, a latex, or similar form. Examples of suitable organic binders include, but are not limited to, acrylic latex, (meth)acrylic latex, phenolic resins, copolymers of styrene and butadiene, vinylpyridine, acrylonitrile, copolymers of acrylonitrile and styrene, vinyl chloride, polyurethane, copolymers of vinyl acetate and ethylene, polyamides, organic silicones, organofunctional silanes, unsaturated polyesters, epoxy resins, polyvinyl esters (such as polyvinylacetate or polyvinylbutyrate latexes) and the like.

The organic binder, if present, may be included in the fire barrier layer in an amount of from 0 to about 40 weight percent, in some embodiments from 0 to about 20 weight percent, based upon the total weight of the fire barrier layer.

Solvents for the binders, if needed, can include water or a suitable organic solvent, such as acetone, for the binder utilized. Solution strength of the binder in the solvent (if used) can be determined by conventional methods based on the binder loading desired and the workability of the binder system (viscosity, solids content, etc.).

In certain embodiments, the fire barrier layer may comprise from about 20% to about 100% by weight of the inorganic platelet material, from 0% to about 40% by weight of the organic binder and/or inorganic binder, and from 0% to about 50% of the functional filler.

In further embodiments, the fire barrier layer may comprise from about 60% to about 100% by weight of the inorganic platelet material, from 0% to about 20% by weight of the organic binder and/or inorganic binder, and from 0% to about 20% of the functional filler.

The fire barrier film laminate and/or the fire barrier layer may additionally comprise a water repellant additive or coating. The water repellant additive or coating may be a component of the fire barrier layer or may be a distinct coating or layer within the fire barrier film laminate, or may be saturated or impregnated into the fire barrier layer. The water repellant additive may alternatively or additionally be present in the adhesives which may be utilized in the subject fire barrier laminate. Without limitation, the water repellant additive or coating may comprise a water repellant silicone; a metal chloride salt such as calcium chloride, magnesium chloride, sodium chloride, potassium chloride, or aluminum chloride; silane; fluorinated compounds or fluorosurfactants such as polytetrafluoroethylene resin; polymeric wet strength resins such as polyamide resin or polyamide-epichlorohydrin resin; mixtures thereof, and the like.

The functional filler(s) may include, but not be limited to, non-platelet clays (such as attapulgite, kyanite, palygorskite, silimanite, or andalucite), fumed silica, boron nitride, cordierite and the like. According to certain embodiments, the functional fillers may include finely divided metal oxides, which may comprise at least one of pyrogenic silicas, arc silicas, low-alkali precipitated silicas, fumed silica, silicon dioxide aerogels, aluminum oxides, titania, calcia, magnesia, potassia, and mixtures thereof.

In certain embodiments, the functional filler may comprise endothermic fillers such as alumina trihydrate, magnesium carbonate, and other hydrated inorganic materials including cements, hydrated zinc borate, calcium sulfate (gypsum), magnesium ammonium phosphate, magnesium hydroxide and combinations thereof. In further embodiments, the functional filler(s) may include lithium-containing minerals. In still further embodiments, the functional fillers(s) may include fluxing agents and/or fusing agents.

In certain embodiments, the functional filler may comprise fire retardant fillers such as antimony compounds, magnesium hydroxide, hydrated alumina compounds, borates, carbonates, bicarbonates, inorganic halides, phosphates, sulfates, organic halogens or organic phosphates.

The fire barrier layer may be directly or indirectly coated onto a film, for example, without limitation, by roll or reverse roll coating, gravure or reverse gravure coating, transfer coating, spray coating, brush coating, dip coating, tape casting, doctor blading, slot-die coating, or deposition coating. In certain embodiments, the fire barrier layer is coated onto the film as a slurry of the ingredients in a solvent, such as water, and is allowed to dry prior to incorporation into the fire barrier laminate. The fire barrier layer may be created as a single layer or coating, thus utilizing a single pass, or may be created by utilizing multiple passes, layers or coatings. By utilizing multiple passes, the potential for formation of defects in the fire barrier layer is reduced. If multiple passes are desired, the second and possible subsequent passes may be formed onto the first pass while the first pass is still substantially wet, i.e. prior to drying, such that the first and subsequent passes are able to form a single unitary fire barrier layer upon drying.

When multiple passes, layers or coatings of the fire barrier layer are utilized, it is possible to vary the amounts of the ingredients in each pass, layer or coating, such that the passes, layers or coatings may have different amounts of, for example, inorganic platelet material. In certain embodiments, at least one pass, layer or coating having a greater amount of inorganic platelet material may be present on the “hot face” of the fire barrier layer. Further, in certain embodiments another pass, layer or coating may have a greater amount of functional filler in order to reduce the amount of defects present in the pass, layer or coating, and may have a greater ability to correct defects present in a previous pass, layer or coating.

In certain embodiments, the fire barrier layer may be directly or indirectly coated onto a first polymeric flame propagation resistant film, such as but not limited to polyesters, polyimides, polyetherketones, polyetheretherketones, polyvinylfluorides, polyamides, polytetrafluoroethylenes, polyaryl sulfones, polyester amides, polyester imides, polyethersulfones, polyphenylene sulfides, ethylene chlorotrifluoroethylene, combinations thereof, and the like. Commercially available examples of these films are films sold by E.I. DuPont de Nemours & Co. of Wilmington, Del., such as a polyester film sold under the trade designation MYLAR®, a polyvinylfluoride film sold under the trade designation TEDLAR®, and a polyimide film sold under the trade designation KAPTON®, a polyetheretherketone film sold under the trade designation APTIV® by Victrex, plc of Lancashire, UK, a polyetheretherketone film sold under the trade designation KETASPIRE® and an ethylene chlorotrifluoroethylene film sold under the trade designation HALAR® by Solvay SA of Brussels, Belgium, and the like. The first polymeric flame propagation resistant film may be metalized to minimize moisture absorption, particularly on the outboard side, but optionally on the inboard side also.

In certain embodiments, the first polymeric flame propagation resistant film and/or the metalized first polymeric flame propagation resistant film may have an opaque, low-gloss polymer coating, optionally containing a fire retardant additive. The fire retardant additives may comprise at least one of antimony compounds, hydrated alumina compounds, borates, carbonates, bicarbonates, inorganic halides, phosphates, sulfates, organic halogens or organic phosphates.

The fire barrier laminate may additionally include an adhesive on one of the outer surfaces to facilitate thermal or other energetic bonding of the laminate to companion backside films as currently practiced in the fabrication of thermal acoustic insulation blankets to form a covering, bag, or envelope for the insulation layers. In some embodiments, a partially or substantially totally encapsulated insulation system is formed. (Air holes may be employed to accommodate pressure variation during flight.) In certain embodiments, the adhesive comprises an adhesive which is activated by the application of ultrasonic or radio frequency energy, or the like.

Optionally, at least one scrim layer may be disposed within the adhesive or a surface adjacent to an adhesive on at least one side of, or within, the fire barrier laminate, in order to, for example, add strength to the laminate, including puncture or tear resistance. In certain embodiments, a scrim may be disposed between the at least one non-fibrous fire barrier layer and the first polymeric flame propagation resistant film layer, such that the non-fibrous fire barrier layer may be coated indirectly onto the flame propagation resistant film layer by coating the non-fibrous fire barrier layer onto the scrim. The scrim may be in the form of a mesh, and may comprise fiberglass, nylon, polyester (such as aromatic polyester), aramid (such as para-aramid), or high or ultra-high molecular weight polyethylene in various embodiments, or may be absent.

The fire barrier laminate may additionally include adhesives, internal to the fire barrier laminate, which are utilized to laminate or otherwise adhere the layers of the fire barrier laminate to one another. These adhesives may include thermally-activated or pressure-based adhesives. The adhesives may comprise at least one of polyester based adhesives or polyvinyl fluoride based adhesives, and/or silicone adhesives. In certain embodiments, the adhesives may contain fire retardant additives. The fire retardant additives may comprise at least one of antimony compounds, hydrated alumina compounds, borates, carbonates, bicarbonates, inorganic halides, phosphates, sulfates, organic halogens or organic phosphates.

As shown in FIG. 1A, an embodiment of a thermal acoustic insulation system 10, or “blanket”, is depicted in cross-section, in which two insulating layers 14, such as one inch thick MICROLITE AA® Premium NR fiberglass insulation (0.42 pcf) (available from Johns Manville International, Inc.), are disposed within a covering of an exteriorly facing fire barrier laminate 16, and an interiorly facing inboard cover film 18 (optionally, a second fire barrier laminate). The insulating layers 14 may also or alternatively comprise polyimide foam insulation. The exteriorly facing laminate 16 and the inboard film 18 may be heat sealed with an adhesive 12 to partially or substantially totally envelop or encapsulate the fiberglass insulation layers. Flames 20, depicting the FAA test procedures, are shown proximate to the exteriorly facing fire barrier laminate 16.

A detail section of an embodiment of the fire barrier laminate 16, encircled as B′ in FIG. 1A is shown in an exploded cross-sectional view in FIG. 1B. The fire barrier laminate 16 is constructed by first applying an adhesive 104 to a first polymeric flame propagation resistant film 106, such as a polyetheretherketone film. The fire barrier layer 102 is then coated onto the adhesive 104-coated first polymeric film 106. Alternatively, the adhesive 104 may be omitted, resulting in the fire barrier layer 102 being coated directly onto the first polymeric film 106. The fire barrier layer 102 may comprise a paste or slurry type material with an amount of water or other solvent being present in the fire barrier layer 102 as it is being coated onto the first polymeric film 106. In this instance, the fire barrier layer 102 is allowed to dry before continued processing. Optionally, a water-repellant material may be incorporated in, coated onto or saturated/impregnated into the fire barrier layer 102.

Separately, a scrim layer 108, such as a fiberglass or nylon scrim, is laminated to a second film 110, such as a polyetheretherketone film, using an adhesive 114. An adhesive 112 is also used to laminate the fire barrier layer 102-coated first polymeric film 106 to the scrim layer 108. Alternatively, the scrim layer 108 may be adhered to the fire barrier layer 102 prior to laminating the scrim layer 108 to the second film 110.

Optionally, the assembled fire barrier laminate 16 includes an encapsulating adhesive layer 116 adjacent to the first polymeric film 106 in order to encapsulate the insulation layers 14 between the fire barrier laminate 16 and the inboard film 18. Additionally or alternatively, the fire barrier laminate 16 may utilize mechanical fasteners or tapes for encapsulating the insulating layers 14 between the fire barrier laminate 16 and the inboard film 18.

A detail section of another embodiment of the fire barrier laminate 16, encircled as B′ in FIG. 1A is shown in an exploded cross-sectional view in FIG. 1C. The fire barrier laminate 16 is constructed by first applying an adhesive 204 to a first polymeric flame propagation resistant film 206, such as a ethylene chlorotrifluoroethylene film. The fire barrier layer 202 is then coated onto the adhesive 204-coated first polymeric film 206. Alternatively, the adhesive 204 may be omitted, resulting in the fire barrier layer 202 being coated directly onto the first polymeric film 206. The fire barrier layer 202 may comprise a paste or slurry type material with an amount of water or other solvent being present in the fire barrier layer 202 as it is being coated onto the first polymeric film 206. In this instance, the fire barrier layer 202 is allowed to dry before continued processing. Optionally, a water-repellant material may be incorporated in, coated onto or saturated/impregnated into the fire barrier layer 202.

A second film 210, such as a metalized polyetheretherketone film, is laminated to the fire barrier layer 202-coated first polymeric film 206 using an adhesive 212. The fire barrier laminate 16 includes a scrim layer 208 laminated to the first polymeric film 206 opposite the fire barrier layer 202 via an adhesive layer 216.

A detail section of a further embodiment of the fire barrier laminate 16, encircled as B′ in FIG. 1A is shown in an exploded cross-sectional view in FIG. 1D. The fire barrier laminate 16 is constructed by first applying an adhesive 304 to a first polymeric flame propagation resistant film 306, such as a metalized polyetheretherketone film. The fire barrier layer 302 is then coated onto the adhesive 304-coated first polymeric film 306. Alternatively, the adhesive 304 may be omitted, resulting in the fire barrier layer 302 being coated directly onto the first polymeric film 306. The fire barrier layer 302 may comprise a paste or slurry type material with an amount of water or other solvent being present in the fire barrier layer 302 as it is being coated onto the first polymeric film 306. In this instance, the fire barrier layer 302 is allowed to dry before continued processing. Optionally, a water-repellant material may be incorporated in, coated onto or saturated/impregnated into the fire barrier layer 302.

Separately, a scrim layer 308, such as a fiberglass or nylon scrim, is laminated to a second film 310, such as a polyetheretherketone film. An adhesive 312 is also used to laminate the fire barrier layer 302-coated first polymeric film 306 to the scrim layer 308. Alternatively, the scrim layer 308 may be adhered to the fire barrier layer 302 prior to laminating the scrim layer 308 to the second film 310.

The assembled fire barrier laminate 16 may include an encapsulating adhesive layer 316 adjacent to the first polymeric film 306 in order to encapsulate the insulation layers 14 between the fire barrier laminate 16 and the inboard film 18. A second scrim layer 308 a is optionally embedded in the adhesive layer 316.

A detail section of a further embodiment of the fire barrier laminate 16, encircled as B′ in FIG. 1A is shown in an exploded cross-sectional view in FIG. 1E. The fire barrier laminate 16 is constructed by first applying an adhesive 404 to a first polymeric flame propagation resistant film 406, such as a polyetheretherketone film. A second scrim layer 408 a is optionally laminated between the adhesive 404 and the first polymeric film 406. The fire barrier layer 402 is then coated onto the adhesive 404-coated first polymeric film 406. Alternatively, the adhesive 404 may be omitted, resulting in the fire barrier layer 402 being coated directly onto the first polymeric film 406. The fire barrier layer 402 may comprise a paste or slurry type material with an amount of water or other solvent being present in the fire barrier layer 402 as it is being coated onto the first polymeric film 406. In this instance, the fire barrier layer 402 is allowed to dry before continued processing. Optionally, a water-repellant material may be incorporated in, coated onto or saturated/impregnated into the fire barrier layer 402.

A second film 410, such as a metalized polyetheretherketone film, is laminated to the fire barrier layer 402-coated first polymeric film 406 using an adhesive 412. The fire barrier laminate 16 includes a scrim layer 408 laminated to the first polymeric film 406 opposite the fire barrier layer 402 via an adhesive layer 416.

The following examples are set forth merely to further illustrate the subject fire barrier layer and fire barrier film laminate. The illustrative examples should not be construed as limiting the fire barrier layer and/or fire barrier laminate in any manner.

Sample 1 comprised a fire barrier layer containing suspended exfoliated vermiculite flakes, silicone binder and water. The fire barrier layer was applied to a polyetheretherketone (PEEK) film which had previously been coated with a silicone adhesive and allowed to dry. Separately, a second PEEK film was laminated to a nylon scrim using a silicone laminating adhesive. The scrim side of the laminate was laminated to the fire barrier layer side of the fire barrier layer-coated PEEK film to form a fire barrier laminate. A heat seal adhesive was then applied to the face of the fire barrier laminate opposite the second PEEK film. The fire barrier laminate final construction had a basis weight of 97 gsm and passed the test protocols of 14 C.F.R. §25.856(a) and (b), described below.

Sample 2 comprised a fire barrier layer containing suspended exfoliated vermiculite flakes and water. The fire barrier layer was applied to a polyetheretherketone (PEEK) film which had previously been coated with a modified natural rubber adhesive and allowed to dry. Separately, a second PEEK film was laminated to a nylon scrim using a poly(amide) laminating adhesive. The scrim side of the laminate was laminated to the fire barrier layer side of the fire barrier layer-coated PEEK film to form a fire barrier laminate. A heat seal adhesive was then applied to the face of the fire barrier laminate opposite the second PEEK film and a fiberglass scrim was incorporated onto the heat seal adhesive-coated face. The fire barrier laminate final construction had a basis weight of 90 gsm and passed the test protocols of 14 C.F.R. §25.856(a) and (b), described below.

Sample 3 comprised a fire barrier layer containing suspended exfoliated vermiculite flakes, silicone binder and water. The fire barrier layer was applied to a polyetheretherketone (PEEK) film which had previously been coated with a modified natural rubber adhesive and allowed to dry. Separately, a second PEEK film was laminated to a nylon scrim using a poly(amide) laminating adhesive. The scrim side of the laminate was laminated to the fire barrier layer side of the fire barrier layer-coated PEEK film to form a fire barrier laminate. A heat seal adhesive was then applied to the face of the fire barrier laminate opposite the second PEEK film. The fire barrier laminate final construction had a basis weight of 103 gsm and passed the test protocols of 14 C.F.R. §25.856(a) and (b), described below.

Sample 4 comprised a fire barrier layer containing suspended exfoliated vermiculite flakes, silicone binder and water. The fire barrier layer was applied to a polyetheretherketone (PEEK) film which had previously been coated with a modified natural rubber adhesive and allowed to dry. Separately, an ethylene chlorotrifluoroethylene (ECTFE) film was laminated to a nylon scrim using a silicone laminating adhesive. The scrim side of the laminate was laminated to the fire barrier layer side of the fire barrier layer-coated PEEK film to form a fire barrier laminate. A heat seal adhesive was then applied to the external face of the ECTFE film. The fire barrier laminate final construction had a basis weight of 95 gsm and passed the test protocols of 14 C.F.R. §25.856(a) and (b), described below.

Sample 5 comprised a fire barrier layer containing suspended exfoliated vermiculite flakes and water. The fire barrier layer was applied to a polyetheretherketone (PEEK) film which had previously been coated with a modified natural rubber adhesive and allowed to dry. Separately, a second PEEK film was laminated to a nylon scrim using a silicone laminating adhesive. The scrim side of the laminate was laminated to the fire barrier layer side of the fire barrier layer-coated PEEK film to form a fire barrier laminate. A heat seal adhesive was then applied to the face of the fire barrier laminate opposite the second PEEK film and a nylon scrim was incorporated onto the heat seal adhesive-coated face. The fire barrier laminate final construction had a basis weight of 105 gsm and passed the test protocols of 14 C.F.R. §25.856(a) and (b), described below.

For testing according to 14 C.F.R. §25.856(a), the fire barrier laminate of each of the Samples 1-5 was used to encapsulate two (2) 1 inch layers of 0.34 pcf MICROLITE AA® premium fiberglass insulation with LAMAGUARD® 131 MD companion polymer film. The fire barrier laminate was heat sealed in order to encapsulate the fiberglass insulation.

For testing according to 14 C.F.R. §25.856(b) the fire barrier laminate of each of the Samples 1-5 was used to encapsulate one (1) 1 inch layer of 0.34 pcf MICROLITE AA® premium fiberglass insulation with LAMAGUARD® 131 MD companion polymer film. The fire barrier laminate was mechanically sealed using staples in order to encapsulate the fiberglass insulation.

Test Protocols

The fire barrier film laminate-protected thermal/acoustic insulation blankets described above were tested according to the protocols of 14 C.F.R. §25.856(a) and (b), Appendix F, Parts VI and VII, which are incorporated herein in their entirety, as if fully written out below.

14 C.F.R. §25.856(a) and (b) provide in pertinent part:

TABLE 2 § 25.856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the fuselage must meet the flame propagation test requirements of part VI of Appendix F to this part, or other approved equivalent test requirements. (b) For airplanes with a passenger capacity of 20 or greater, thermal/acoustic insulation materials (including the means of fastening the materials to the fuselage) installed in the lower half of the airplane fuselage must meet the flame penetration resistance test requirements of part VII of Appendix F to this part, or other approved equivalent test requirements.

Appendix F Part VI provides, in pertinent part:

TABLE 3 Part VI—Test Method To Determine the Flammability and Flame Propagation Characteristics of Thermal/Acoustic Insulation Materials Use this test method to evaluate the flammability and flame propagation characteristics of thermal/acoustic insulation when exposed to both a radiant heat source and a flame. (a) Definitions. “Flame propagation” means the furthest distance of the propagation of visible flame towards the far end of the test specimen, measured from the midpoint of the ignition source flame. Measure this distance after initially applying the ignition source and before all flame on the test specimen is extinguished. The measurement is not a determination of burn length made after the test. “Radiant heat source” means an electric or air propane panel. “Thermal/acoustic insulation” means a material or system of materials used to provide thermal and/or acoustic protection. Examples include fiberglass or other batting material encapsulated by a film covering and foams. “Zero point” means the point of application of the pilot burner to the test specimen. (b) Test apparatus. (4) Pilot Burner. The pilot burner used to ignite the specimen must be a Bernzomatic ™ commercial propane venturi torch with an axially symmetric burner tip and a propane supply tube with an orifice diameter of 0.006 inches (0.15 mm). The length of the burner tube must be 2 7/8 inches (71 mm). The propane flow must be adjusted via gas pressure through an in-line regulator to produce a blue inner cone length of 3/4 inch (19 mm). A 3/4 inch (19 mm) guide (such as a thin strip of metal) may be soldered to the top of the burner to aid in setting the flame height. The overall flame length must be approximately 5 inches long (127 mm). Provide a way to move the burner out of the ignition position so that the flame is horizontal and at least 2 inches (50 mm) above the specimen plane. (5) Thermocouples. Install a 24 American Wire Gauge (AWG) Type K (Chromel-Alumel) thermocouple in the test chamber for temperature monitoring. Insert it into the chamber through a small hole drilled through the back of the chamber. Place the thermocouple so that it extends 11 inches (279 mm) out from the back of the chamber wall, 11 1/2 inches (292 mm) from the right side of the chamber wall, and is 2 inches (51 mm) below the radiant panel. The use of other thermocouples is optional. (6) Calorimeter. The calorimeter must be a one-inch cylindrical water- cooled, total heat flux density, foil type Gardon Gage that has a range of 0 to 5 BTU/ft²-second (0 to 5.7 Watts/cm²). (c) Test specimens. (1) Specimen preparation. Prepare and test a minimum of three test specimens. If an oriented film cover material is used, prepare and test both the warp and fill directions. (2) Construction. Test specimens must include all materials used in construction of the insulation (including batting, film, scrim, tape etc.). Cut a piece of core material such as foam or fiberglass, and cut a piece of film cover material (if used) large enough to cover the core material. Heat sealing is the preferred method of preparing fiberglass samples, since they can be made without compressing the fiberglass (“box sample”). Cover materials that are not heat sealable may be stapled, sewn, or taped as long as the cover material is over-cut enough to be drawn down the sides without compressing the core material. The fastening means should be as continuous as possible along the length of the seams. The specimen thickness must be of the same thickness as installed in the airplane. (3) Specimen Dimensions. To facilitate proper placement of specimens in the sliding platform housing, cut non-rigid core materials, such as fiberglass, 12 1/2 inches (318 mm) wide by 23 inches (584 mm) long. Cut rigid materials, such as foam, 11 1/2 ± 1/4 inches (292 mm ± 6 mm) wide by 23 inches (584 mm) long in order to fit properly in the sliding platform housing and provide a flat, exposed surface equal to the opening in the housing. (d) Specimen conditioning. Condition the test specimens at 70 ± 5° F. (21° ± 2° C.) and 55% ± 10% relative humidity, for a minimum of 24 hours prior to testing. (f) Test Procedure. (1) Ignite the pilot burner. Ensure that it is at least 2 inches (51 mm) above the top of the platform. The burner must not contact the specimen until the test begins. (2) Place the test specimen in the sliding platform holder. Ensure that the test sample surface is level with the top of the platform. At “zero” point, the specimen surface must be 7 1/2 inches ± 1/8 inch (191 mm ± 3) below the radiant panel. (3) Place the retaining/securing frame over the test specimen. It may be necessary (due to compression) to adjust the sample (up or down) in order to maintain the distance from the sample to the radiant panel (7 1/2 inches ± 1/8 inch (191 mm ± 3) at “zero” position). With film/fiberglass assemblies, it is critical to make a slit in the film cover to purge any air inside. This allows the operator to maintain the proper test specimen position (level with the top of the platform) and to allow ventilation of gases during testing. A longitudinal slit, approximately 2 inches (51 mm) in length, must be centered 3 inches ± 1/2 inch (76 mm ± 13 mm) from the left flange of the securing frame. A utility knife is acceptable for slitting the film cover. (4) Immediately push the sliding platform into the chamber and close the bottom door. (5) Bring the pilot burner flame into contact with the center of the specimen at the “zero” point and simultaneously start the timer. The pilot burner must be at a 27° angle with the sample and be approximately 1/2 inch (12 mm) above the sample. A stop . . . allows the operator to position the burner correctly each time. (6) Leave the burner in position for 15 seconds and then remove to a position at least 2 inches (51 mm) above the specimen. (g) Report. (1) Identify and describe the test specimen. (2) Report any shrinkage or melting of the test specimen. (3) Report the flame propagation distance. If this distance is less than 2 inches, report this as a pass (no measurement required). (4) Report the after-flame time. (h) Requirements. (1) There must be no flame propagation beyond 2 inches (51 mm) to the left of the centerline of the pilot flame application. (2) The flame time after removal of the pilot burner may not exceed 3 seconds on any specimen.

Appendix F Part VII provides, in pertinent part:

TABLE 4 Part VII—Test Method To Determine the Burnthrough Resistance of Thermal/Acoustic Insulation Materials Use the following test method to evaluate the burnthrough resistance characteristics of aircraft thermal/acoustic insulation materials when exposed to a high intensity open flame. (a) Definitions. Burnthrough time means the time, in seconds, for the burner flame to penetrate the test specimen, and/or the time required for the heat flux to reach 2.0 Btu/ft²sec (2.27 W/cm²) on the inboard side, at a distance of 12 inches (30.5 cm) from the front surface of the insulation blanket test frame, whichever is sooner. The burnthrough time is measured at the inboard side of each of the insulation blanket specimens. Insulation blanket specimen means one of two specimens positioned in either side of the test rig, at an angle of 30° with respect to vertical. Specimen set means two insulation blanket specimens. Both specimens must represent the same production insulation blanket construction and materials, proportioned to correspond to the specimen size. (b) Apparatus. (3) Calibration rig and equipment. (i) Construct individual calibration rigs to incorporate a calorimeter and thermocouple rake for the measurement of heat flux and temperature. Position the calibration rigs to allow movement of the burner from the test rig position to either the heat flux or temperature position with minimal difficulty. (ii) Calorimeter. The calorimeter must be a total heat flux, foil type Gardon Gage of an appropriate range such as 0-20 Btu/ft²-sec (0-22.7 W/cm²), accurate to ±3% of the indicated reading. The heat flux calibration method must be in accordance with paragraph VI(b)(7) of this appendix. (iv) Thermocouples. Provide seven 1/8-inch (3.2 mm) ceramic packed, metal sheathed, type K (Chromel-alumel), grounded junction thermocouples with a nominal 24 American Wire Gauge (AWG) size conductor for calibration. Attach the thermocouples to a steel angle bracket to form a thermocouple rake for placement in the calibration rig during burner calibration. (5) Backface calorimeters. Mount two total heat flux Gardon type calorimeters behind the insulation test specimens on the back side (cold) area of the test specimen mounting frame. Position the calorimeters along the same plane as the burner cone centerline, at a distance of 4 inches (102 mm) from the vertical centerline of the test frame. (i) The calorimeters must be a total heat flux, foil type Gardon Gage of an appropriate range such as 0-5 Btu/ft²-sec (0-5.7 W/cm²), accurate to ±3% of the indicated reading. The heat flux calibration method must comply with paragraph VI(b)(7) of this appendix. (6) Instrumentation. Provide a recording potentiometer or other suitable calibrated instrument with an appropriate range to measure and record the outputs of the calorimeter and the thermocouples. (7) Timing device. Provide a stopwatch or other device, accurate to ±1%, to measure the time of application of the burner flame and burnthrough time. (c) Test Specimens. (1) Specimen preparation. Prepare a minimum of three specimen sets of the same construction and configuration for testing. (2) Insulation blanket test specimen. (i) For batt-type materials such as fiberglass, the constructed, finished blanket specimen assemblies must be 32 inches wide by 36 inches long (81.3 by 91.4 cm), exclusive of heat sealed film edges. (3) Construction. Make each of the specimens tested using the principal components (i.e., insulation, fire barrier material if used, and moisture barrier film) and assembly processes (representative seams and closures). (i) Fire barrier material. If the insulation blanket is constructed with a fire barrier material, place the fire barrier material in a manner reflective of the installed arrangement For example, if the material will be placed on the outboard side of the insulation material, inside the moisture film, place it the same way in the test specimen. (v) Conditioning. Condition the specimens at 70° ± 5° F. (21° ± 2° C.) and 55% ± 10% relative humidity for a minimum of 24 hours prior to testing. (f) Test procedure. (1) Secure the two insulation blanket test specimens to the test frame. The insulation blankets should be attached to the test rig center vertical former using four spring clamps . . . (according to the criteria of paragraph (c)(4) or (c)(4)(i) of this part of this appendix). (2) Ensure that the vertical plane of the burner cone is at a distance of 4 ± 0.125 inch (102 ± 3 mm) from the outer surface of the horizontal stringers of the test specimen frame, and that the burner and test frame are both situated at a 30° angle with respect to vertical. (3) When ready to begin the test, direct the burner away from the test position to the warm-up position so that the flame will not impinge on the specimens prematurely. Turn on and light the burner and allow it to stabilize for 2 minutes. (4) To begin the test, rotate the burner into the test position and simul- taneously start the timing device. (5) Expose the test specimens to the burner flame for 4 minutes and then turn off the burner. Immediately rotate the burner out of the test position. (6) Determine (where applicable) the burnthrough time, or the point at which the heat flux exceeds 2.0 Btu/ft²-sec (2.27 W/cm²). (g) Report. (1) Identify and describe the specimen being tested. (2) Report the number of insulation blanket specimens tested. (3) Report the burnthrough time (if any), and the maximum heat flux on the back face of the insulation blanket test specimen, and the time at which the maximum occurred. (h) Requirements. (1) Each of the two insulation blanket test specimens must not allow fire or flame penetration in less than 4 minutes. (2) Each of the two insulation blanket test specimens must not allow more than 2.0 Btu/ft²-sec (2.27 W/cm²) on the cold side of the insulation specimens at a point 12 inches (30.5 cm) from the face of the test rig.

In a first embodiment, a subject fire barrier laminate may comprise: at least one non-fibrous fire barrier layer directly or indirectly coated onto at least one first polymeric flame propagation resistant film layer; at least one second film layer proximate to the non-fibrous fire barrier layer opposite the first polymeric flame propagation resistant film layer; at least one scrim layer disposed: (i) between the non-fibrous fire barrier layer and the first polymeric flame propagation resistant film layer; and/or (ii) between the non-fibrous fire barrier layer and the second film layer; and/or (iii) proximate to the first polymeric flame propagation resistant film layer opposite the non-fibrous fire barrier layer; and/or (iv) proximate to the second film layer opposite the non-fibrous fire barrier layer; optionally, a water-repellant material incorporated into and/or applied to the non-fibrous fire barrier layer; optionally at least one adhesive layer adhering the non-fibrous fire barrier layer to the first polymeric flame propagation resistant film layer; and optionally at least one adhesive layer adhering the scrim layer to at least one of the non-fibrous fire barrier layer, the first polymeric flame propagation resistant film layer, or the second film layer; wherein the non-fibrous fire barrier layer comprises at least one inorganic platelet material, optionally at least one organic binder and/or inorganic binder, and optionally at least one functional filler.

The fire barrier laminate of the first embodiment may further include that the inorganic platelet material comprises at least one of vermiculite, mica, clay or talc. The vermiculite may be exfoliated and optionally defoliated. The clay may comprise at least one of ball clay, bentonite, smectite, hectorite, kaolinite, montmorillonite, saponite, sepiolite or sauconite.

The fire barrier laminate of either or both of the first or subsequent embodiments may further include that the organic binder comprises at least one of acrylic latex, (meth)acrylic latex, phenolic resins, copolymers of styrene and butadiene, vinylpyridine, acrylonitrile, copolymers of acrylonitrile and styrene, vinyl chloride, polyurethane, copolymers of vinyl acetate and ethylene, polyamides, silicones, unsaturated polyesters, epoxy resins or polyvinyl esters.

The fire barrier laminate of any of the first or subsequent embodiments may further include that the inorganic binder comprises at least one of colloidal alumina, colloidal silica or colloidal zirconia.

The fire barrier laminate of any of the first or subsequent embodiments may further include that the non-fibrous fire barrier layer comprises from about 20% to about 100% by weight of the inorganic platelet material, from 0% to about 40% by weight of the organic binder and/or inorganic binder, and from 0% to about 50% of the functional filler.

The fire barrier laminate of any of the first or subsequent embodiments may further include that the non-fibrous fire barrier layer comprises from about 60% to about 100% by weight of the inorganic platelet material, from 0% to about 20% by weight of the organic binder and/or inorganic binder, and from 0% to about 20% of the functional filler.

The fire barrier laminate of any of the first or subsequent embodiments may further include that either or both of the first polymeric flame propagation resistant film layer or the second film layer comprises at least one of polyesters, polyimides, polyetherketones, polyetheretherketones, polyvinylfluorides, polyamides, polytetrafluoroethylenes, polyaryl sulfones, polyester amides, polyester imides, polyethersulfones, polyphenylene sulfides, ethylene chlorotrifluoroethylene, or combinations thereof.

The fire barrier laminate of any of the first or subsequent embodiments may further include that the at least one scrim layer comprises at least one of fiberglass, nylon, polyester, aramid, or high or ultra-high molecular weight polyethylene.

The fire barrier laminate of any of the first or subsequent embodiments may further include that either or both of the first polymeric flame propagation resistant film layer and the second film layer are metalized. Either or both of the first polymeric flame propagation resistant film layer or the second film layer have an opaque, low-gloss polymer coating, optionally including a fire retardant additive.

The fire barrier laminate of any of the first or subsequent embodiments may have a basis weight of less than about 120 gsm.

In a second embodiment, a subject thermal acoustic insulation system may comprise a plurality of insulating layers disposed within a covering of an exteriorly facing fire barrier laminate as in any of the first or subsequent embodiments, and an interiorly facing inboard cover film.

The thermal acoustic insulation system of the second embodiment may further include that the interiorly facing cover film also comprises the fire barrier laminate.

The thermal acoustic insulation system of either or both of the second or subsequent embodiments may further include that the exteriorly facing fire barrier laminate and the interiorly facing inboard cover film are sealed with an adhesive to partially or substantially totally envelop or encapsulate the plurality of insulating layers.

The thermal acoustic insulation system of any of the second or subsequent embodiments may further include that the insulating layers comprise fiberglass insulation and/or polyimide foam insulation.

The thermal acoustic insulation system of any of the second or subsequent embodiments may be capable of passing the flame propagation and burn-through resistance test protocols of 14 C.F.R. §25.856(a) and (b), Appendix F, Parts VI and VII.

In a third embodiment, a subject method of making a fire barrier laminate may comprise: directly or indirectly coating at least one non-fibrous fire barrier layer onto a first polymeric flame propagation resistant film layer; laminating the non-fibrous fire barrier layer with at least one second film layer, wherein the second film layer is proximate to the non-fibrous fire barrier layer; and laminating at least one scrim layer within the fire barrier laminate, wherein the at least one scrim layer is disposed: (i) between the non-fibrous fire barrier layer and the first polymeric flame propagation resistant film layer; and/or (ii) between the non-fibrous fire barrier layer and the second film layer; and/or (iii) proximate to the first polymeric flame propagation resistant film layer opposite the non-fibrous fire barrier layer; and/or (iv) proximate to the second film layer opposite the non-fibrous fire barrier layer; wherein the non-fibrous fire barrier layer comprises at least one inorganic platelet material, optionally at least one organic binder and/or inorganic binder, and optionally at least one functional filler; and wherein the non-fibrous fire barrier layer optionally contains a water repellant material, and/or the method further comprises optionally coating and/or saturating the non-fibrous fire barrier layer with a water repellant material.

The method of the third embodiment may further include that the inorganic platelet material comprises at least one of vermiculite, mica, clay or talc. The vermiculite may be exfoliated and optionally defoliated.

The method of either or both of the third or subsequent embodiments may further include that the organic binder comprises at least one of acrylic latex, (meth)acrylic latex, phenolic resins, copolymers of styrene and butadiene, vinylpyridine, acrylonitrile, copolymers of acrylonitrile and styrene, vinyl chloride, polyurethane, copolymers of vinyl acetate and ethylene, polyamides, silicones, unsaturated polyesters, epoxy resins or polyvinyl esters.

The method of any of the third or subsequent embodiments may further include that the inorganic binder comprises at least one of colloidal alumina, colloidal silica or colloidal zirconia.

The method of any of the third or subsequent embodiments may further include that the non-fibrous fire barrier layer comprises from about 20% to about 100% by weight of the inorganic platelet material, from 0% to about 40% by weight of the organic binder and/or inorganic binder, and from 0% to about 50% of the functional filler.

The method of any of the third or subsequent embodiments may further include that either or both of the first polymeric flame propagation resistant film layer or the second film layer comprises at least one of polyesters, polyimides, polyetherketones, polyetheretherketones, polyvinylfluorides, polyamides, polytetrafluoroethylenes, polyaryl sulfones, polyester amides, polyester imides, polyethersulfones, polyphenylene sulfides, ethylene chlorotrifluoroethylene, or combinations thereof.

The method of any of the third or subsequent embodiments may further include that the at least one scrim layer comprises at least one of fiberglass, nylon, polyester, aramid, or high or ultra-high molecular weight polyethylene.

The method of any of the third or subsequent embodiments may further include that either or both of the first polymeric flame propagation resistant film layer or the second film layer are metalized. Either or both of the first polymeric flame propagation resistant film layer or the second film layer may be coated with an opaque, low-gloss polymer, optionally including a fire retardant additive.

It will be understood that the embodiments described herein are merely illustrative, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described hereinabove. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result. 

1. A method of making a fire barrier laminate comprising: directly or indirectly coating at least one non-fibrous fire barrier layer onto a first polymeric flame propagation resistant film layer; laminating the non-fibrous fire barrier layer with at least one second film layer, wherein the second film layer is proximate to the non-fibrous fire barrier layer; and laminating at least one scrim layer with the fire barrier laminate, wherein the at least one scrim layer is disposed: (i) between the non-fibrous fire barrier layer and the first polymeric flame propagation resistant film layer; and/or (ii) between the non-fibrous fire barrier layer and the second film layer; and/or (iii) proximate to the first polymeric flame propagation resistant film layer opposite the non-fibrous fire barrier layer; and/or (iv) proximate to the second film layer opposite the non-fibrous fire barrier layer; wherein the non-fibrous fire barrier layer comprises at least one inorganic platelet material, optionally at least one organic binder and/or inorganic binder, and optionally at least one functional filler; and wherein the non-fibrous fire barrier layer optionally contains a water-repellant material, and/or the method further comprises optionally coating and/or saturating the non-fibrous fire barrier layer with a water-repellant material.
 2. The method of claim 1, wherein the inorganic platelet material comprises at least one of vermiculite, mica, clay or talc.
 3. The method of claim 2, wherein the vermiculite is exfoliated and optionally defoliated.
 4. The method of claim 1, wherein the organic binder comprises at least one of acrylic latex, (meth)acrylic latex, phenolic resins, copolymers of styrene and butadiene, vinylpyridine, acrylonitrile, copolymers of acrylonitrile and styrene, vinyl chloride, polyurethane, copolymers of vinyl acetate and ethylene, polyamides, silicones, unsaturated polyesters, epoxy resins or polyvinyl esters.
 5. The method of claim 1, wherein the inorganic binder comprises at least one of colloidal alumina, colloidal silica or colloidal zirconia.
 6. The method of claim 1, wherein the non-fibrous fire barrier layer comprises from about 20% to about 100% by weight of the inorganic platelet material, from 0% to about 40% by weight of the organic binder and/or inorganic binder, and from 0% to about 50% of the functional filler.
 7. The method of claim 1, wherein either or both of the first polymeric flame propagation resistant film layer or the second film layer comprises at least one of polyesters, polyimides, polyetherketones, polyetheretherketones, polyvinylfluorides, polyamides, polytetrafluoroethylenes, polyaryl sulfones, polyester amides, polyester imides, polyethersulfones, polyphenylene sulfides, ethylene chlorotrifluoroethylene, or combinations thereof
 8. The method of claim 1, wherein the at least one scrim layer comprises at least one of fiberglass, nylon, polyester, aramid, or high or ultra-high molecular weight polyethylene.
 9. The method of claim 1, wherein either or both of the first polymeric flame propagation resistant film layer or the second film layer are metalized.
 10. The method of claim 9, further comprising coating either or both of the first polymeric flame propagation resistant film layer or the second film layer with an opaque, low-gloss polymer, optionally including a fire retardant additive. 